1. Field of the Invention
This invention relates generally to the prediction of dynamics of a vehicle and, more particularly, to a recursive method for predicting vehicle dynamics using information about a path on which the vehicle is travelling for enhancing active safety performance of the vehicle and to improve driver comfort.
2. Description of the Related Art
Most modern vehicles are equipped with vehicle control (VC) systems that enhance the safety and comfort of the occupants of the vehicle. VC systems constantly monitor and control, if required, various vehicle parameters, such as yaw, side-slip and roll of the vehicle. In general, sensors are used to monitor vehicle parameters, such as those mentioned above, along with certain driver inputs, such as rotation of the steering wheel and brake and throttle applications. VC systems receive signals from these sensors and keep the vehicle stable and under control by taking certain actions.
It can be said that the VC systems currently found in the art are largely feedback based. The feedback mechanism of such systems sometimes makes them slow to respond in real time situations. In other situations, a quick and aggressive control action taken by the VC system in response to signals from the sensors can lead to discomfort of the driver and other occupants, and also to the vehicle going out of control. Keeping in mind the above-mentioned concerns, VC systems can be made more effective by incorporating early prediction of dynamic states of the vehicle, such as vehicle spinning and rollover.
One existing method for predicting the dynamics of a vehicle only makes use of the conventional on-board vehicle sensors, such as vehicle speed sensors, lateral and longitudinal acceleration sensors, steering angle sensors and yaw-rate sensors, to make the predictions. However, the inability of a technique to base this prediction on other sensor inputs, such as lane/path from vision and GPS/map database, compromises the system's ability and results in an unreliable prediction.
Another known method for predicting the dynamics of a vehicle makes use of a mathematical model. However, this method assumes the steering angle to be constant for a pre-determined time period in the future, which is seldom the case. Further, the method does not take into account the corrections made by the driver and different driving styles.
Another known method for predicting and compensating the dynamics of a vehicle makes use of the transmission of information between two vehicles. Vehicle control systems base their response on information received from a vehicle travelling just ahead of the concerned vehicle. However, this method may not be practical for predicting vehicle dynamics due to its naturally small bandwidth and slow response compared to fast vehicle dynamics.